How it all began...
The Gebr. Ruhstrat company was founded in 1888 by the brothers Adolf and Ernst Ruhstrat in Göttingen, Germany. The business was initially located at Lange Geismarstraße 74, then also at Lange Geismarstraße 72/73. The electrical store developed into a modern medium-sized family business.
In 1894 the Ruhstrat brothers, in cooperation with the Nobel Prize winner Prof. Walter Nernst, University of Göttingen, created the basis for setting or changing resistances as well as current and voltage with the adjustable slide resistor. He supplied the first private homes and businesses in Göttingen with electricity using electrical block stations and developed the electricity meter. In close cooperation with the university, the company grew rapidly and after the end of World War I it was the largest specialized factory for electrical resistors.
Further development led to the construction of the first resistance-heated high-temperature furnace in 1896 and, from 1898, to the transfer of the construction of high-temperature furnaces for industrial purposes to the "Elektromechanische Werkstätten Gebr. Ruhstrat". Since that time Ruhstrat manufactured high-tech industrial furnaces up to 3000° C for various heat treatments, together with the transformers necessary for their operation. In 1916 Ruhstrat delivered the first emergency lighting systems with single batteries. In the following years, the concentration on the production and sale of transformers, power resistors, safety power supplies and resistance-heated industrial furnaces was further increased. 
 Employee registration Ruhstrat 31.12.1944, Bundesarchiv Außenstelle Lichterfelde, R 12 1/102 (Reichsgruppe Industrie) (information provided by Frank Baranowski)